Re: [PATCH bpf-next v3 3/3] selftests/bpf: Add test for using css_task iter in sleepable progs

[Yonghong Song <yonghong.song@linux.dev>]

On 10/25/23 12:59 AM, Chuyi Zhou wrote:
> This Patch add a test to prove css_task iter can be used in normal
> sleepable progs.
>
> Signed-off-by: Chuyi Zhou <zhouchuyi@bytedance.com>
> ---
>   .../selftests/bpf/progs/iters_task_failure.c  | 19 +++++++++++++++++++
>   1 file changed, 19 insertions(+)
>
> diff --git a/tools/testing/selftests/bpf/progs/iters_task_failure.c b/tools/testing/selftests/bpf/progs/iters_task_failure.c
> index 6b1588d70652..fe0b19e545d0 100644
> --- a/tools/testing/selftests/bpf/progs/iters_task_failure.c
> +++ b/tools/testing/selftests/bpf/progs/iters_task_failure.c
> @@ -103,3 +103,22 @@ int BPF_PROG(iter_css_task_for_each)
>   	bpf_cgroup_release(cgrp);
>   	return 0;
>   }
> +
> +SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
> +int BPF_PROG(iter_css_task_for_each_sleep)
> +{
> +	u64 cg_id = bpf_get_current_cgroup_id();
> +	struct cgroup *cgrp = bpf_cgroup_from_id(cg_id);
> +	struct cgroup_subsys_state *css;
> +	struct task_struct *task;
> +
> +	if (cgrp == NULL)
> +		return 0;
> +	css = &cgrp->self;
> +
> +	bpf_for_each(css_task, task, css, CSS_TASK_ITER_PROCS) {
> +
> +	}
> +	bpf_cgroup_release(cgrp);
> +	return 0;
> +}

Could you move this prog toiters_css_task.c and add a subtest in cgroup_iter.c? The file 
iters_task_failure.c intends for negative tests. This prog succeeds with 
loading.